Facebook, Instagram and Twitter have suspended Geofeedia, a platform that collects real-time social media information based on location, from having access to its data.

The decision follows an investigation that law enforcement used the tool to track activists and protests, the American Civil Liberties Union of North California (ACLU) published in a blog post Tuesday. It provides another case that surveillance information is potentially being used to target minority groups.

Geofeedia pulls social media feeds and makes it searchable and accessible to third parties (Mashable is a customer). Subscribers can search by keyword and by location to find recently posted and publicly available tweets.

The information is accessible at least 500 law enforcement and public safety agencies as of June, according to an email from Geofeedia published by ACLU.

Geofeedia, for its part, does not deny selling its data to law enforcement agencies. It noted “major law enforcement agencies like the Los Angeles County Sheriff’s Department” as a subscriber in its Series A funding round announcement in 2014.

Yet, the ACLU investigation highlighted the tool’s surveillance capabilities, which is against these social media platforms’ rules. The ACLU posted emails from Geofeedia’s team that mentioned the tool’s ability to track the protests in Ferguson, Missouri, and Baltimore.

The confidential emails from Geofeedia published by ACLU also say that the platform is able to “pull private information for Instagram and Twitter users.”

The ACLU reached out to the companies about the situation with Geofeedia. For instance, The Daily Dot reported via a public record request that the Denver Police Department uses Geofeedia. The Baltimore Sun reported that its police also used Geofeedia to monitor protests, parades and celebrations.

Geofeedia did not immediately respond to a request for comment.

Based on information in the @ACLU’s report, we are immediately suspending @Geofeedia’s commercial access to Twitter data.

Facebook’s platform policy also states that developers cannot “sell license, or purchase any data obtained from us or our services” and they cannot “transfer any data that [they] receive from us (including anonymous, aggregate, or derived data) to any … data broker.”

Facebook said in a statement to Mashable, “This developer only had access to data that people chose to make public. Its access was subject to the limitations in our Platform Policy, which outlines what we expect from developers that receive data using the Facebook Platform. If a developer uses our APIs in a way that has not been authorized, we will take swift action to stop them and we will end our relationship altogether if necessary.”